Generic inheritance question

[Mugworth]

Hello,
I would like to ask if there is any way to document generic function that return superclass of arguement

---@Generic L
---@Generic T: L
---@type fun(class: T): superclass: L: table
oo.getsuper = cached.getsuper

... Is what im thinking about but of course it does not work that way,
maybe you guys have any idea if its doable?

[tomlau10]

I don't think there is a way, because in LuaLS a class just a type container, and it can have multiple inheritance. So there is no single superclass for any class. 😕 As for Lua itself, it is a dynamic typed language, and we often call it duck typing.

https://www.lua.org/pil/16.3.html

16.3 – Multiple Inheritance

[tomlau10]

If you really want to annotate a getsuper method, the only way that I can think of is to add the method def for every class that support it (which is not generic). This is similar to no generic way to create inheritance annotation, you have to write ---@class Child: Base explicitly to create a class-inheritance annotation.

---@class Base
---@field baseId integer
---@field getsuper fun(self): nil
local Base

---@class Mixin
---@field mixinId integer
local Mixin

---@class Child: Base, Mixin
---@field childId integer
---@field getsuper fun(self): Base
local Child

local a = Base:getsuper()   -- nil
local b = Child:getsuper()  -- Base